Apparatus for recording and/or reproducing information and/or optical information record disk

ABSTRACT

An apparatus for recording and/or reproducing information on and/or from a magneto-optical disk including an optical head for projecting a laser beam onto a magneto-optical disk and receiving the laser beam reflected by the disk, an up-down block arranged movably between a lower position and an upper position, an up-down motor for moving said up-down block up and down, a turntable for supporting the disk and a spindle motor secured to said up-down block and having a driving shaft coupled with said turntable for rotating the turntable, a position detecting device for detecting a position of said up-down block to derive a position signal when the up-down block is driven into the upper position, a rotation detecting device for detecting a rotation of said optical information record disk to derive a rotation signal when the optical information record disk is rotated at a predetermined revolving speed, and a control device for initiating a focus control for moving said objective lens and turntable relative to each other in accordance with said position signal and rotation signal.

This application is a continuation of application Ser. No. 09/320,460,filed May 27, 1999 (U.S. Pat. No. 6,078,550), which was a continuationof application Ser. No. 09/182,890, filed Oct. 30, 1998 now U.S. Pat.No. 5,940,357, which was a continuation of application Ser. No.08/744,558, filed Nov. 6, 1996 (U.S. Pat. No. 5,862,110), which was acontinuation of application Ser. No. 08/466,433, filed Jun. 6, 1995(abandoned), which was a continuation of application Ser. No.08/225,977, filed Apr. 12, 1994 (U.S. Pat. No. 5,446,711).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for recording and/orreproducing information on and/or from an optical record disk comprisingan optical head including a semiconductor laser for emitting a laserbeam, an objective lens for projecting the laser beam emitted by thesemiconductor laser onto the optical information record disk and aphotodetecting means for receiving a return laser beam reflected by saidoptical information record disk to produce information signal andfocusing error signal; a disk driving device including a turntable forsupporting the optical information record disk and s spindle motor forrotating said turntable together with the optical information recorddisk; means for driving at said objective lens in a radial direction ofthe optical information record disk; and a control means for performinga focus control for moving said objective lens and turntable relative toeach other for moving a relative position of a focus point of the laserbeam with respect to the optical information record disk in a focusingdirection which is parallel with an optical axis of said objective lens.

2. Related Art Statement

In Japanese Patent Application Publication No. 1-35415 published on Jul.25, 1989, there is described a known apparatus for recording and/orreproducing information on and/or from an optical information recorddisk such as the magneto-optical record disk. In this known apparatus,when the cartridge having an optical disk installed therein is insertedinto the apparatus, the cartridge is inserted into a holder of acartridge loading mechanism and this holder is movably arranged on adriving member, and when the cartridge is fully inserted into theholder, the driving member is moved downward so that the optical disk isplaced on a turntable which is coupled with a driving shaft of a spindlemotor. In this apparatus, the optical disk can be place on the turntablewithout moving the spindle motor and turntable up and down, so that thedisk driving device may be simple in construction. However, the holderhas to be moved not only horizontally, but also vertically, andtherefore the mechanism for driving the holder is liable to becomplicated and a stable operation could be hardly attained.

In order to avoid the above mentioned drawbacks, there has been proposedanother known apparatus described in Japanese Patent ApplicationLaid-open Publication Kokai Hei No. 4-321972 published on Nov. 11, 1992.In this known optical information record disk apparatus, after acartridge having a magneto-optical record disk installed therein isinserted into the apparatus, a spindle motor for rotating the opticaldisk is moved upward such that the optical disk is supported by aturntable provided on a driving shaft of the spindle motor. In thisknown apparatus, it is no more necessary to provide a mechanism fordescending the cartridge in the cartridge loading mechanism, and thusits construction becomes simple and small. Further, in this knownapparatus, a focus control including focus search and focus servo isperformed by moving the spindle motor, turntable and optical disk in adirection parallel with an axis of the spindle motor such that adistance between the objective lens and the information record plane ofthe optical disk is changed. Therefore, it is no more necessary toprovide, in the optical head, an objective lens driving mechanism formoving the objective lens in a direction of its optical axis and thusthe optical head can be made small in size and light in weight. Itshould be noted that the focus servo control means a control foradjusting a distance between the objective lens and the optical disk inaccordance with a focusing error signal by means of a focus servomechanism so that the light beam is correctly focused on the opticaldisk, and the focus search control means a control for setting saiddistance within a controllable range of the focus servo mechanism.

In this known apparatus, the spindle motor is secured to an up-downblock, and turntable and cartridge positioning member are secured to theup-down block. When the up-down block is moved upward, a lower surfaceof the cartridge is supported by projections of the cartridgepositioning member and an optical disk installed within the cartridge issupported on the turntable. The disk is firmly secured onto theturntable by means of a permanent magnet. The up-down block is moved upand down by a cum mechanism including a cum gear and a up-down motor forrotating the cum gear by means of a gear box, a cum surface of said cumgear being engaged with a roller arranged rotatably on a side surface ofthe up-down block. A rotation of the cum gear is detected by a rotaryencoder, so that a position of the up-down block can be detected byprocessing an output signal of the rotary encoder.

In this known apparatus, the position of the up-down block is notdirectly detected, but is presumed from the rotation of the cum gear. Bysuch an indirect detection, the position of the up-down block could notbe accurately detected owing to the reason that the gears contain backrush and thus the output signal detected by the rotary encoder could notprecisely represent an amount of the actual up-down movement of theup-down block. It should be noted that the focus control including thefocus search and focus servo has to be performed in relation to aposition of a movable portion including the up-down block, turntable,cartridge positioning member and spindle motor, but in the knownapparatus the position of the movable member could not be detectedprecisely and it is no more possible to perform the focus controlprecisely.

Further, in the known disk driving device, substantial parts of thedevice including the up-down block, spindle motor, turntable andcartridge positioning member are moved up and down, and thus arelatively heavy load is applied to the up-down motor. Therefore, theup-down motor is liable to be large. Moreover, during the focus control,not only the turntable, but also the up-down block and spindle motor aremoved up and down, the projections of the cartridge positioning membermight vibrate and thus the projections might hit the cartridge toproduce annoying noise.

SUMMARY OF THE INVENTION

The present invention has for its object to provide a novel and usefulapparatus for recording and/or reproducing information on and/or from anoptical information record disk, in which the position of the up-downblock can be detected precisely, so that the focus control can becarried out accurately and reliably.

It is another object of the invention to provide a novel and usefulapparatus for recording and/or reproducing information on and/or from anoptical information record disk, in which the focus control can beperformed without moving the up-down block and spindle motor, so thatthe focus control can be effected accurately.

It is still another object of the invention to provide a novel anduseful apparatus for recording and/or reproducing information on and/orfrom an optical record disk, in which a focus control can be initiatedstably and reliably.

According to the invention, an apparatus for recording and/orreproducing information on and/or from an optical record disk comprises:

an optical head including a semiconductor laser for emitting a laserbeam, an objective lens for projecting the laser beam emitted by thesemiconductor laser onto the optical information record disk and aphotodetecting means for receiving a return laser beam reflected by saidoptical information record disk to produce information signal andfocusing error signal;

a disk driving means including an up-down block arranged movably in adirection perpendicular to a plane of the optical information recorddisk between a lower position and an upper position, an up-down motorfor moving said up-down block between said lower position and upperposition, a turntable for supporting the optical information record diskand a spindle motor secured to said up-down block and having a drivingshaft coupled with said turntable for rotating the turntable togetherwith the optical information record disk;

an optical head driving means for driving at least said objective lensin a radial direction of the optical information record disk;

a position detecting means for detecting directly a position of saidup-down block to derive a position signal when the up-down block isdriven into said upper position;

a rotation detecting means for detecting a rotation of said opticalinformation record disk to derive a rotation signal when the opticalinformation record disk is rotated at a predetermined revolving speed;and

a control means for initiating a focus control for moving said objectivelens and turntable relative to each other in accordance with saidposition signal and rotation signal.

According to a preferable embodiment of the apparatus according to theinvention, said turntable of said driving means is arranged on a drivingshaft of said spindle motor such that the turntable is rotated togetherwith the driving shaft but is slidable along the driving shaft, and saiddisk driving means comprises a first driving device for moving theup-down block up and down and a second driving device for moving saidturntable up and down along the driving shaft of the spindle motor.

According to further aspect of the invention, an apparatus for recordingand/or reproducing information on and/or from an optical record diskcomprises:

an optical head including a semiconductor laser for emitting a laserbeam, an objective lens for projecting the laser beam emitted by thesemiconductor laser onto the optical information record disk and aphotodetecting means for receiving a return laser beam reflected by saidoptical information record disk to produce information signal andfocusing error signal;

a disk driving means including an up-down block arranged movably in adirection perpendicular to a plane of the optical information recorddisk between a lower position and an upper position, an up-down motorfor moving said up-down block between said lower position and upperposition, a turntable for supporting the optical information record diskand a spindle motor secured to said up-down block and having a drivingshaft coupled with said turntable for rotating the turntable togetherwith the optical information record disk;

an optical head driving means for driving at least said objective lensin a radial direction of the optical information record disk;

a position detecting means for detecting directly a position of saidup-down block to derive a position signal when the up-down block isdriven into said upper position;

a control means for initiating an energization of said spindle motor forrotating the optical information record disk in accordance with saidposition signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a half cross sectional and half front view showing anembodiment of the disk driving means of the optical informationrecording and/or reproducing apparatus according to the invention;

FIG. 2 is a schematic view depicting a whole construction of theapparatus;

FIG. 3 is a plan view representing the objective lens driving unit;

FIG. 4 is a perspective exploded view illustrating the objective lensdriving unit;

FIG. 5 is a flow chart explaining the operation of the apparatus;

FIG. 6 is a side view showing another embodiment of the disk drivingdevice according to the invention;

FIG. 7 is a side view of the disk driving device of FIG. 6 in acondition in which the cartridge is not fully inserted;

FIG. 8 is a side view illustrating a modification of the disk drivingdevice shown in FIG. 6;

FIG. 9 is a cross sectional view depicting another embodiment of thedisk driving device according to the invention; and

FIG. 10 is a bottom view of the device illustrated in FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now the present invention will be explained in detail with reference tothe drawings.

FIG. 1 is a half cross sectional and half front view of a disk drivingdevice of an embodiment of the optical information recording and/orreproducing apparatus according to the invention. In the presentembodiment, a magneto-optical disk installed within a cartridge issupported by a turntable formed by a spindle cup and is rotated by aspindle motor. FIG. 2 shows an optical head and a focus control systemof the present embodiment.

As shown in FIG. 1, the disk driving device comprises a main body 201and a spindle motor 204 which is arranged above the main body movably upand down by means of an up-down block 273. That is to say, the spindlemotor 204 is secured to the up-down block 273 which is arranged movablyup and down. On a driving shaft 288 of the spindle motor 204, a spindlecup 275 is arranged slidably along the driving shaft, but is rotatedtogether with the driving shaft 288. To this end, a key 287 extending inan axial direction of the driving shaft 288 is secured to the drivingshaft and this key is slidably inserted into a recess formed in an innerwall of the spindle cup 275. An upper surface of the spindle cup 275forms a turntable 241 for the optical disk as will be explained later.

To an upper portion of the spindle motor 204 is secured a ring-shapedelectromagnet 271, and a ring-shaped permanent magnet 272 is secured toa bottom surface of the spindle cup 275 such that they are faced witheach other. As will be explained later, the permanent magnet 272 isrotated by the spindle motor 204 and the electromagnet 271 is sometimesbrought into contact with the rotating permanent magnet 272. In order toprevent the electromagnet 271 from being damaged by said slidingcontact, the electromagnet is covered with a plastic housing.

In the up-down block 273, there are formed through holes 273 a extendingin parallel with an axial direction of the driving shaft of the spindlemotor 204, and guide shafts 274 secured to the main body 201 areinserted into the through holes such that the up-down block 273 issmoothly moved up and down along the guide shafts 274. The up-down block273 extends in the axial direction such that it substantially surroundsthe spindle cup 275 and includes at least three projections 276. Whenthe up-down block 273 is driven into an upper position, round front endsof the projections 276 are brought into contact with a round edge of arecess formed in a lower surface of the cartridge 251, so that thecartridge is positioned with respect to the up-down block 273 and thusthe driving shaft 288 of the spindle motor 204. It should be noted thattips of these projections 273 a situate on a plane which isperpendicular to the axial direction of the driving shaft 288.

To a side wall of the up-down block 273 is secured a rack gear 278 whichengages with a pinion gear 279, and this pinion gear 279 is driven by anup-down motor 280 arranged on the main body 201. Therefore, by drivingthe up-down motor 280, it is possible to move the up-down block 273 andthus the spindle motor 204 up and down. Between the main body 201 andthe lower surface of the up-down block 272 at the guide shafts 274,there are arranged compressing coiled springs 281 such that the up-downblock is biased to move upward.

On a lower surface of the spindle motor 204 there is secured a lightreflecting member 282 by an adhesive agent. The light reflecting member282 comprises a glass plate on which a metal thin film is coated. Theglass plate may be formed in a wedge-shaped one. On the main body 201there is secured a photoreflector 283 by an adhesive agent at a positioncorresponding to the reflecting member 282. The photoreflector 283 iswell known in the art and may be formed by a unit including a lightemitting diode and two light receiving regions.

The magneto-optical disk 242 installed within the cartridge 251 has adisk hub 277 made of magnetic material secured to a central hole of thedisk by means of an adhesive agent. To the spindle cup 275 is secured aring-shaped magnetic yoke 284 and a ring-shaped permanent magnet 285 issecured to the yoke. Therefore, when the spindle cup 275 is moved upwardand a distance between the yoke 284 and the magnetic hub 277 of the disk242 becomes smaller than a given value, the disk hub 277 is attracted bythe yoke 284 as illustrated in FIG. 1. In this manner, according to thisembodiment, when the up-down block 273 is moved upward by means of theup-down motor 280, the positioning of the disk 242 with respect to theaxis of the spindle cup 275 can be obtained and at the same time themagneto-optical disk 242 is firmly coupled with the spindle cup.

In the present embodiment, the up-down block 273 having the spindlemotor 204 secured thereto and the spindle cup 275 can be moved up anddown independently from each other. That is to say, the spindle cup 275is coupled with the driving shaft 288 of the spindle motor 204 such thatthe spindle cup can be moved up and down with respect to the drivingshaft by supplying a driving current to the electromagnet 271.Therefore, the focus search and focus servo can be performed withoutmoving the up-down block 273. On the other hand, the spindle cup 275 hasto be rotated by the spindle motor 204, so that the spindle cup iscoupled with the driving shaft of the spindle motor 204 by means of akey and recess coupling mechanism. That is to say, a key 289 extendingin the axial direction of the driving shaft 288 is secured to thedriving shaft, and a recess is formed in a side wall of the spindle cup275, said key being inserted into the recess.

In the present embodiment, there are provided the first drivingmechanism (278, 279, 280) for moving the up-down block 273, i.e. thespindle motor 204 in the up and down directions with respect to thespindle cup 275 and the second driving mechanism (271, 272) for movingthe spindle cup 275 in the up and down directions with respect to thespindle motor 204.

To the driving shaft of the spindle motor 204 is secured a stopper 286,and between the stopper 286 and the spindle cup 275 is arranged a coiledspring 287 for biasing the spindle cup downward. Therefore, when theelectromagnet 271 is not energized, the spindle cup 275 is driven to thelower position so that the permanent magnet 27 is brought into contactwith the electromagnet 271.

As illustrated in FIG. 2, the optical pick-up apparatus comprises astational optical unit 202 and an objective lens driving unit 203, theseunits being arranged on the main body 201. The stational optical unit233 comprises semiconductor laser 221, collimator lens 222, prism 230having first and second beam splitters 231 and 232, half wavelengthplate 261, collecting lens 262, polarizing beam splitter 263 and firstand second photodetectors 224 and 264. The objective lend driving unit203 comprises a carriage 233, reflection prism 332 and objective lens333. The carriage 233 is arranged movably in a radial direction of themagneto-optical disk 242 by means of a suitable driving mechanism suchas a linear motor not shown. A laser beam emitted by the semiconductorlaser 221 is converted into a parallel beam by means of the collimatorlens 222 and is then made incident upon the first beam beam splitter231. A laser beam reflected by the first beam splitter 231 is receivedby the first photodetector 224 and an output signal of the firstphotodetector is supplied to an automatic power control circuit (APC)225 which controls the output power of the semiconductor laser 221 inaccordance with the output signal from the first photodetector 224.

The output signal of the first photodetector 224 is also supplied to acontrol device (CPU) 207 of a focus control system. The focus controlsystem includes in addition to this CPU 207 focus driving circuit 206and switch SW. In order to initiate the focus search or focus control,to the control device 207 are supplied a detection signal of therotation of the magneto-optical disk 242 and a detection signal of theup-down movement of the spindle motor 204. That is to say, an outputsignal SPDP of the photoreflector 283 and an output signal of an encoder(not shown) fro detecting the rotation of the spindle motor 204 aresupplied to the control device 207. The switch SW is controlled by thecontrol device 207 in accordance with these output signals. The abovementioned electromagnet 271 is connected to the driving circuit 206.

A laser beam transmitted through the first beam splitter 231 is thenmade incident upon the second beam splitter 232 and a laser beamtransmitted through the second beam splitter 232 emanates from thestational optical unit 202 toward the objective lens driving unit 203.

Now the carriage 233 of the objective lens driving unit 203 will beexplained in detail.

FIGS. 3 and 4 are plan and exploded perspective views, respectivelyshowing the carriage 233. The carriage 233 is arranged on a slide guide233A comprising movable member 341, elongated stationary member 342secured to the main body 201 and retainer 343 and is moved along theslide guide in the radial direction of the magneto-optical disk 242.

A carriage main body 233B is formed by a plate-like member, and thisplate-like member is inserted between upper and lower coil portions 337Uand 337D of an access coil 377 and is secured to the access coil. Thatis to say, lower and upper surfaces 233 a and 233 b of the plate-likemember 233B are cemented to the lower and upper coil portions 337D and377U, respectively by means of an adhesive agent.

The reflecting prism 332 of the objective lens driving unit 203 ismounted on a projection 233 c of the carriage main body 233B and issecured thereto by cementing. The objective lens 333 is supported by alens holder 344 in the form of a box having openings, and the reflectingprism 332 and projection 233 c are inserted into the lens holder throughone opening such that the reflecting prism 332 faces the objective lens333.

A projection 233 d of the carriage main body 233B is inserted into arecess 344 a formed in a supporting block 344 and is secured thereto byan adhesive agent. In this manner, the supporting block 344 is fixed tothe carriage main body 233B.

In a lower surface of the supporting block 344 there is formed adepression 344 b into which the movable member 341 can extend. In thesupporting block 344 there is further formed a through hole 344 c forpassing the laser beam. Surfaces of side projections 344 d and 344eformed in the upper and lower surfaces of the supporting block 334 aresecured to a base portion of a leaf spring unit 336 by cementing. Theleaf spring unit 336 comprises four leaf springs 336 a to 336 d whosefree ends are secured to the lens holder 334. In this manner, the lensholder 334 and thus the objective lens 333 can be supported to beresiliently moved at least in a focusing direction parallel with anoptical axis of the objective lens 333 as well as a tracking directionperpendicular both to the optical axis and an information track on themagneto-optical disk 242.

On the lens holder 334 there are wound tracking coils 335 which areinserted into spaces 337 b formed between permanent magnets 338 andinner yokes 340 which constitute a magnetic circuit of the linear motortogether with outer yokes 339. The access coil 337 is arranged tosurround or embrace the inner yokes 340, so that the movable portionincluding the access coil 337, carriage main body 233B, supporting block344 and lens holder 334 is moved linearly along the slide guide 233A bysupplying a current to the access coil.

As explained above the front ends of the leaf springs 336 a to 336 d aresecured to the lens holder 334. The leaf springs 336 a to 336 d haveexpanding and shrinking portions 336 e to 336 h, respectively, each ofwhich is formed by a mesh woven from very fine wires and a rubbercoating applied on the mesh. When the lens holder 334 is moved in thetracking direction, the expanding and shrinking portions 336 e to 336 hare deformed in a plane of the drawing of FIG. 3. Further, the lensholder 334 can be moved in the radial direction of the magneto-opticaldisk 242 even if the carriage main portion 233B is stationary.

The carriage main body 233B is guided along the slide guide 233A bymeans of an intermediate member 345. That is to say, upper surfaces 345a of upper projections of the intermediate member 345 are cemented ontothe lower surface of the carriage main body 233B such that the portion337U of the access coil 377 is clamped between the intermediate memberand the carriage main body, and further the movable member 341 isclamped into a recess 345 b formed in the lower surface of theintermediate member 345 and is cemented thereto by a suitable adhesiveagent.

The permanent magnets 338 and outer and inner yokes 339 and 340 aresecured to the main body 201 and the outer and inner yokes are coupledwith each other at their ends to form the closes magnetic circuits. Itshould be noted that sizes of the lens holder 344, access coil 337,permanent magnet 338 and yokes 339, 340 are so determined that thesmooth movement of the carriage main body 233B is not affected.

When the current is supplied to the access coil 337, the carriage mainbody 233B is moved together with the movable portion 341 in the radialdirection of the magneto-optical disk 242 along the slide guide 233A.Further the tracking control can be performed by supplying the trackingcontrol signal to the tracking coils 335. That is to say, the trackingcoils 335 cooperate with the magnetic field formed by the permanentmagnets 338 and yokes 339, 340 to move the carriage main body 233B, i.e.the lens holder 334 in the radial direction of the disk 242. In thismanner, according to the invention, the magnetic circuit composed of thepermanent magnets 338 and yokes 339, 340 is utilized both for the linearmovement of the carriage main body 233B and the tracking control.Furthermore, according to the invention, the focus search and focuscontrol are performed not by moving the objective lens 333 in thedirection of its optical axis, but by moving the magneto-optical disk242 by means of the electromagnet 271 and permanent magnet 272.Therefore, it is not necessary to provide the focusing mechanismincluding the permanent magnet and focusing coil in the lens holder, sothat the objective lens driving device 203 can be further made small insize and light in weight and can be manufactured easily in a lessexpensive manner.

The parallel laser beam emanating from the stationary unit 202 is madeincident upon the reflecting prism 332 and is reflected thereby upwardlyand is made incident upon the objective lens 333. The laser beam is thenmade incident upon the magneto-optical disk 242. The return laser beamreflected by the magneto optical disk 242 is made incident upon thestationary unit 202 by means of the objective lens 333 and reflectingprism 332.

The return laser beam is reflected by the second beam splitter 232 inthe optical system 260 and is made incident upon the half wavelengthplate 261 so that its polarizing direction is rotated by 45 degrees.Then the return beam is made incident upon the polarizing beam splitter263 by means of the collecting lens 262. The polarizing beam splitter263 serves as the analyzer and P-polarized component is transmittedthrough the polarizing beam splitting plane and S-polarized component isreflected by the polarizing beam splitting plane, and these P-polarizedand S-polarized components are received by separate light receivingelements of the photodetector 264.

By suitably processing outputs of the light receiving elements of thephotodetector 264, it is possible to derive a focusing error signalrepresenting a deviation of the focuses spot of the beam with respect tothe information record plane of the magneto-optical disk 242 in thedirection of the optical axis, a tracking error signal denoting adeviation of the focus point of the beam with respect to the informationtrack in the radial direction, and an information signal representingthe information recorded on the magneto-optical disk.

As shown in FIG. 2, there is provided a magnetic head 205 above the disk242 and the magnetic head is secured to a supporting arm not shown. Thesupporting arm is driven such that the magnetic head 205 is alwaysindexed into a position facing the objective lens driving unit 203 viathe disk 242.

The focusing error signal is supplied to a focus control circuit 206 bymeans of the switch SW controlled by the control device 207. The focuscontrol circuit 206 comprises focus servo control circuit (FOD) 206 aand focus search control circuit (FOS) 206 b. Output terminals of thefocus servo control circuit 206 a and focus search control circuit 206 bare connected to a coil L of the electromagnet 271 arranged on thespindle motor 204. By supplying a control signal having a suitablepolarity to the coil L from the focus control circuit 206, theelectromagnet 271 generates a magnetic field having a given direction toproduce the repelling force in combination with the permanent magnet272, so that the spindle cup 275 on which the disk 242 is mounted ismoved upward against the spring force of the coiled spring 287 and themagneto-optical disk 242 is moved away from the objective lens 333. Inthis manner, by changing the magnitude of the control signal, thedistance between the disk 242 and the objective lens 333 can be adjustedin combination of the repelling force produced by the electromagnet 271and permanent magnet 272 and the resilient force of the coiled spring287.

In the present embodiment, the control device 207 controls not only thefocus control system but also other control systems. For instance, thespindle motor 204, up-down motor 280, linear motor for driving theobjective lens driving unit 203, semiconductor laser 221, and trackingcoils 335 may be controlled by the control device 207.

Now the operation of the present embodiment will be explained also withreference to a flow chart illustrated in FIG. 5.

In FIG. 1, above the main body 201, there is arranged a cartridge holder(not shown). At first, the cartridge 251 is inserted into the cartridgeholder. The cartridge holder and a mechanism for mounting the cartridgeare well known in the art, so that they are not explained further indetail. For instance, the known cartridge holder disclosed in the abovementioned Japanese Patent Application Laid-open Publication Kokai Hei4-351785 may be used. This known cartridge holder has openings at frontand rear sides and the disk is rotatably installed within a cartridge.

The cartridge holder is constructed such that the cartridge 251 can beinserted in parallel with the main body 201. That is to say, when thecartridge 251 is inserted into the cartridge holder, a shutter openingpin on the cartridge holder pushes a shutter of the cartridge 251 inaccordance with the movement of the cartridge, and thus an opening ofthe cartridge on the recording and reproducing side is opened. At thesame time, the cartridge 251 is inserted into a space between theobjective lens driving unit 203 and the magnetic head 205.

When the cartridge 251 has been inserted upto a given complete insertingposition, this is detected by a detector not shown and its detectionsignal is supplied to the control device 207. Then, the control device207 controls the up-down motor 280, so that the up-down block 273 ismoved upward from a lower home position by means of the pinion gear 279and rack gear 278. When the up-down block 273 is moved upward and comesclose to the cartridge 251, the projections 276 of the up-down block 273are brought into contact with the positioning recess formed in the lowersurface of the cartridge 251. At the same time or after that, the hub277 of the disk 242 is attracted onto the turntable 241 of the spindlecup 275 by the attracting force produced by the permanent magnet 285.

When no current is supplied to the coil L of the electromagnet 271, theelectromagnets 271 and permanent magnet 272 are brought into contactwith each other by means of the spring force of the coiled spring 287.The electromagnet 271 and permanent magnet 272 are determined such thatunder said condition there is still formed a necessary space between thelower surface of the cartridge 251 and the disk 242.

During the upward movement of the up-down block 273, the position of theup-down block 273 is detected by the photoreflector 283. That is to say,the photoreflector 283 projects the light beam toward the reflectingmember 282 and the reflected light beam is made incident upon thephotoreflector. A position of the reflected light beam spot on the twolight receiving regions of the photoreflector 283 is changed inaccordance with the distance from the photoreflector and the reflectingmember 282. Therefore, this distance can be detected by deriving adifference between outputs of these light receiving regions 283 a of thephotoreflector 283. The thus detected distance SPDP is supplied to thecontrol device 207.

When it is confirmed that the up-down block 273 has moved into the givenupper position from the output signal of the photoreflector 283, thespindle motor 204 is energized and the disk 242 is rotated together withthe spindle cup 275. To the driving shaft 288 of the spindle motor 204is secured a rotary encoder 291 shown in FIG. 2 and the output signalSPFD of the rotary encoder is converted by a F/V (frequency/voltage) andthe converted voltage is applied to the control device 207.

Before rotating the disk 242, the carriage 233 is moved into the innermost position of the disk. After it is confirmed that the disk has beenrotated at a given constant speed such as 3600 rpm, the control device207 energizes the semiconductor laser 221 to emit the laser beam. Whenthe semiconductor laser 221 emits the laser beam, this is detected bythe first photodetector 224 and the thus detected signal is supplied tothe control device 207. Then, the control device 207 confirms that thelaser beam having a give intensity has been emitted from thesemiconductor laser 221.

In the manner explained above, after confirming that the spindle motor204 and spindle cup 275 have been moved into the upper position, thedisk 242 has been rotated at the given speed, and the semiconductorlaser 221 has emitted the laser beam having the given intensity, thecontrol device 207 initiates the focus control. That is to say, at firstthe focus search control is effected by supplying the focus searchsignal from the focus search control circuit 206 b to the coil L of theelectromagnet 271 under the control of the control device 207. The focussearch control itself is well known in the art, so that this will beexplained only briefly. In the present embodiment, in the initialcondition, the disk 242 is in the nearest position to the objective lens333, so that usually the focus point of the laser beam situates abovethe disk 242. When the focus search control is initiated, the spindlecup 275 is gradually moved upward so that the disk 242 is moved awayfrom the objective lens 333. During this period, the focusing errorsignal generated by the photodetector 264 is supplied to the focussearch control circuit 206 b via the switch SW and this focusing errorsignal is compared with a predetermined threshold level. When thefocusing error signal exceeds the threshold level, it can be confirmedthat the disk 242 has been driven into the dynamic range of the focusservo. Then, the focus search is finished and the focus servo isinitiated by the focus servo control circuit 206 a. That is to say, thecontrol signal supplied to the focus control coil L is changed inaccordance with the focusing error signal supplied from thephotodetector 264 such that the laser beam spot is always focused on theinformation record plane of the disk 242.

As explained above, in the present embodiment, after the control device207 has confirmed that the spindle motor 204 and spindle cup 275 havebeen moved into the upper position and the revolving speed of thespindle motor 204 has increased to the predetermined value, and thesemiconductor laser 221 has emitted the laser beam having thepredetermined intensity, the control device 207 allows the focus searchcontrol and focus servo control.

Therefore, according to the invention, the focus search control andfocus servo control are not performed when the up-down block 201 ismoving and the disk 242 is not rotated at a given revolving speed, sothat the reliability of the apparatus is improved and noise due tomalfunction can be avoided.

Furthermore, after the objective lens driving unit 203 has been movedinto the innermost position, the disk is rotated. Therefore, apossibility that the disk might be brought into contact with theobjective lens driving unit 203 can be minimum, because the disk ishardly bent at the innermost position. Therefore, the focus searchcontrol can be stably and promptly performed.

As stated above, the focus search and focus servo control can be carriedout by supplying the current to the coil L of the electromagnet 271.When the control device 207 allows the initiation of the control of thefocus, at first the focus search signal is supplied to the coil L of theelectromagnet 271 and there is produced a repelling force between theelectromagnet 271 and the permanent magnet 272, so that the spindle cup275 and thus the disk 242 is moved upward against the force of thecoiled spring 287. During this movement, the focusing error signal issupplied to the focus search control circuit 206 b via the switch SW.Therefore, the disk 242 is moved into the dynamic range of the focusservo, and then the focus servo control is initiated. In this case, thefocus servo control signal may be superimposed on the focus searchcontrol signal at the end of the focus search control. Then, the focussearch control can be smoothly and stably transferred to the focus servocontrol without being affected by the inertia of the movable portionincluding the disk 242 and spindle cup 275. After that, the focusingerror signal detected by the photodetector 264 is supplied to the focuscontrol circuit 206 a via the switch SW and the disk 242 is moved up anddown in accordance with the focusing error signal.

In this manner, in the present embodiment, the spindle cup 275constituting the turntable 241 for the disk 242 can be independentlymoved in the axial direction with respect to the up-down block 273 andthe focus search control and focus servo control are performed by movingonly the spindle cup 275. In other words, the focus search control andfocus servo control can be effected without moving the up-down block 273having a large weight. Moreover, the objective lens driving unit 203does not include a permanent magnet for driving the objective lens 333in the focusing direction, and thus the objective lens driving unit canbe made small in size and light in weight and the high speed access canbe attained.

Further, in the present embodiment, the cartridge 251 is stablysupported during the focus search control, so that some members of thecartridge supporting mechanism are not brought into contact with eachother and the generation of noise can be effectively avoided. In thismanner, noise can be removed and the reliability is increased, while theadvantages of the known apparatuses can be still attained.

FIGS. 6 and 7 show another embodiment of the disk driving device of theoptical information recording and/or reproducing apparatus according tothe invention. In the present embodiment, the up and down movement ofthe spindle motor and spindle cup is carried out by means of a swingablemovement of a plate like member. The disk driving device comprises abase member 11 having a flat upper surface and a driving plate 12arranged on the upper surface of the base member 11 such that thedriving plate can slide thereon in a direction A. On the base member 11there are provided a plurality of pins 13 and these pins are insertedinto recesses 14 formed in the driving plate 12 (in FIG. 6, only one ofpins and one of recesses are seen). On the base member 11 there are alsosecured pins 15 and coiled springs 16 are arrange between the pins 15and a left hand projection 12 a of the driving plate 12, so that thedriving plate is biased to be moved in the leftward direction. Thedriving plate 12 further comprises an operating portion 12 b at itsright hand end, said operating portion being gradually bent upwardly.

To both sides of the base member 11 there are secured uprightprojections 17 and a shaft 18 is supported by these projections suchthat the shaft extends horizontally. To the shaft 18, there is swingablysecured a supporting plate 19. The supporting plate 18 is biased by acoiled spring 20 to be rotated in the clockwise direction about theshaft 18. On the supporting plate 19 there is secured an up-down block21 to which a spindle motor is secured. Between the supporting plate 19and the up-down block 21, there are arranged rubber rings 22 serving ascushion. Similar to the first embodiment, the spindle motor secured tothe up-down block 21 includes a driving shaft and a spindle cup 23 isarranged slidably along the driving shaft. On the up-down block 21,there are arranged projections 24 for positioning a cartridge 25 havinga magneto-optical information record disk 26. The disk 26 is firmlyplaced on a turntable formed by the spindle cup 23 by means of themagntic force.

In the present embodiment, in a right hand end of the supporting plate19, there is provided a light emitting diode (LED) 27 and a light beamemitted by the LED is projected downward through a stop 28 having a finehole. In the operating portion 12 b of the driving plate 12, there isformed an opening 29, and on the base member there is provided aphotodetector 30. FIG. 6 shows a condition in which the cartridge 25 hasbeen fully inserted, the driving plate 11 is moved into the left handposition, and an assembly of the up-down block 21, the spindle motor andspindle cup 23 is moved into an upper position so that the cartridge 25is positioned by the projections 24 with respect to the spindle cup andthe disk 26 is placed on the turntable of the spindle cup. In thiscondition, the light beam emitted by the LED 27 is transmitted throughthe opening 29 formed in the operating portion 12 b of the driving plate12 and is made incident upon the photodetector 30.

FIG. 7 illustrates a condition in which the cartridge 25.is removed andthe driving plate 12 is moved into the right hand position, so that thesupporting plate 19 is rotated in the clockwise direction about theshaft 18. Therefore, the projections 24 are removed from the cartridge25 and the spindle cup 23 is removed from the disk. In this condition,the light beam emitted from the LED 27 is shielded by the driving plate12, and thus the light beam is not made incident upon the photodetector30. In the manner explained above, in the present embodiment, theposition of the spindle motor 21 and spindle cup 23 can be directlydetected by monitoring an output signal of the photodetector 30.

FIG. 8 illustrates a modification of the embodiment shown in FIGS. 6 and7, so that portions in FIG. 8 which are similar to those depicted inFIGS. 6 and 7 are denoted by the same reference numerals used in FIGS. 6and 7. In the present embodiment, a photoreflector 31 is arranged on thespindle motor 21 such that a light beam reflected by the cartridge 25can be received by light receiving regions of the photoreflector. In thepresent embodiment, by monitoring an output signal from thephotoreflector 30, it is possible to detect the insertion of thecartridge 25 into the apparatus. When the insertion of the cartridge 25is detected, a trigger lever not shown is driven to move the drivingplate 12 in the left hand direction by means of the action of thesprings 16. Then, the right hand edge of the supporting plate 19 slideson the operating portion 12 b of the driving plate 12, and thus thesupporting plate 19 is rotated in the anti-clockwise direction.Therefore, the cartridge 25 is supported by the projections 24 and thedisk 26 is placed on the spindle cup 23. This can be also detected bythe output signal of the photoreflector 30. Then, the spindle motorsecured to the up-down block 21 is energized to rotate the disk 26 up toa predetermined revolving speed, and after that the focus control isinitiated.

In the present embodiment, the photoreflector 30 can detect not only theupward movement of the up-down block 21, spindle motor and spindle cup23, but also the insertion of the cartridge 25.

FIGS. 9 and 10 illustrate still another embodiment of the disk drivingdevice of the optical recording and/or reproducing apparatus accordingto the invention. In the present invention, the rotating movement istransferred into the up-down movement by means of an inclined recess anda pin. The disk driving device comprises a base member 41 on which aring-shaped support member 42 is secured by means of screws 43. On thesupporting member 42, there is arranged a rotating cylinder 44 and aclamping ring 45 having a thread formed in its inner surface. That is tosay, the supporting ring 42 is clamped between the rotating cylinder 44and the clamping ring 45 such that the rotating cylinder 44 is rotatedabout its longitudinal axis together with the clamping ring 45, butcould not move in the axial direction. On an outer surface of therotating cylinder 44, is secured a arcuate rack gear 46 which is engagedwith a warm gear 47 coupled with a driving shaft of an up-down motor 48.Therefore, by driving the up-down motor 48, it is possible to rotate therotating cylinder 44 about the longitudinal axial direction thereof. Onthe outer surface of the rotating cylinder 44, there is also secured alight shielding plate 49, and a photointerruptor is arranged on the basemember 41 such that the light shielding plate 49 is arranged between alight emitting diode 50 and a photodetector 51.

Within the rotating cylinder 44 is arranged an up-down block 52 havingsecured a spindle motor and a spindle cup 53. The construction of theup-down block 52 with projections 53, spindle motor and spindle cup 54is substantially same as that of the first embodiment shown in FIG. 1.In FIG. 9, the spindle motor is not seen and only an upper portion ofthe spindle cup 54 is seen. In the side wall of the rotating cylinder44, there is formed an inclined recess 55 and on the up-down block 52there is secured a pin 56 which is inserted into the recess 55.Therefore, by rotating the rotating cylinder 44 by means of the motor48, the up-down block 52 is moved up and down. It should be noted thatthe spindle cup 54 can be moved up and down with respect to the spindlemotor and up-down block 52 by means of the magnetic driving mechanismincluding the electromagnet 271 and permanent magnet 272 shown in FIG.1.

FIG. 10 shows a bottom of the disk driving device. In order to preventthe up-down block 52 from being rotated together with the rotatingcylinder 44, in the outer surface of the up-down block, there is formeda recess 57 extending in its axial direction and a guide plate 58 isinserted into the recess 57 such that the up-down block 52 can be movedup and down. In the lower edge of the rotating cylinder 44, there isformed a recess 59, so that the rotation of the rotating cylinder 44 canrotate without being prevented by the guide plate 58.

In the present embodiment, when the cartridge is not fully inserted, therotating cylinder 44 is in a home position at which the up-down block 52is in a lower position P1. After the cartridge is inserted into theapparatus, the up-down motor 48 is energized to rotate the rotatingcylinder 44. Then, the up-down block 52 is moved upward into an upperposition P2. In the upper-position P2, a cartridge is supported by theprojections 53 and a disk is placed on a turntable formed by the spindlecup 54. During the rotation of the rotating cylinder 44, the lightshielding plate 49 is existent between the light emitting diode 50 andthe photodetector 51, and thus a light beam is not made incident uponthe photodetector 51. When the up-down block 52 is driven into the upperposition P2, the light shielding plate 49 is no more existent betweenthe light emitting diode 50 and the photodetector 51, so that the lightbeam is made incident upon the photodetector. Therefore, by monitoringthe output signal from the photodetector 51, it is possible to detectthe position of the up-down block 52. After it is confirmed that thatthe up-down block 52 has been driven into the upper position P2, thespindle motor is energized, and then after it is confirmed that the diskhas been rotated at a given speed, the focus control is initiated.

The present invention is not limited to the above explained embodiments,but many modifications and alternations may be conceived by thoseskilled in the art within the scope of the invention. For instance, inthe above mentioned embodiments, the focus control including the focussearch control and focus servo control are performed by moving theoptical information record disk while the objective lens is remainedstationary in the focusing direction, but according to the invention thefocus control may be carried out by moving the objective lens in adirection of its optical axis.

What is claimed is:
 1. An apparatus for recording and/or reproducinginformation on and/or from an optical record disk, said apparatuscomprising: an optical head including a semiconductor laser for emittinga laser beam, an objective lens for projecting the laser beam emitted bysaid semiconductor laser onto the optical record disk, a firstphoto-detecting means for receiving a return laser beam reflected by theoptical record disk to produce an information signal, and a secondphoto-detecting means for detecting a part of light emitted from thesemiconductor laser; a carriage having said optical head arrangedthereon and being movable in a reciprocal manner between innermost andoutermost positions of the optical record disk in a radial direction ofthe optical record disk; a disk driving means including a movable blockarranged movably between a first position and a second position relativeto said optical record disk, a movable block driving means for movingsaid movable block between said first position and said second position,a turntable for supporting the optical record disk, and a spindle motorsecured to said movable block and having a driving shaft coupled withsaid turntable for rotating the turntable together with the opticalrecord disk; a position detecting means for detecting a position of saidmovable block to derive a position signal when the movable block isdriven into said first position; and a control means for energizing saidsemiconductor laser after confirming that said position signal has beengenerated by said position detecting means and said carriage has beendriven into said innermost position of the optical record disk, and forinitiating focus search or focus control after confirming that laserlight emitted by the semiconductor laser has been received by saidsecond photo-detecting means.
 2. An apparatus according to claim 1,wherein said disk driving means further comprises a permanent magnetwhich presses the turntable against the optical record disk in adirection substantially perpendicular to the optical record disk under acondition that the movable block has been driven into said firstposition.
 3. An apparatus according to claim 1, wherein said turntableof the disk driving means is arranged movably with respect to saidmovable block such that the turntable is moved toward and away from theoptical record disk, and said movable block comprises a positioningmeans for positioning the optical record disk when the movable block isdriven into said first position.
 4. An apparatus according to claim 3,wherein said turntable is brought into contact with the optical recorddisk after positioning the optical record disk by said positioningmeans.
 5. An apparatus according to claim 1, wherein the apparatusfurther comprises a guide means for guiding the optical record diskthrough a space formed between a magnetic field generating means and theobjective lens, when the movable block is in said second position.
 6. Anapparatus according to claim 1, wherein said second photo-detectingmeans detects a part of the laser beam emitted from the semiconductorlaser and impinging upon the objective lens.
 7. An apparatus accordingto claim 1, wherein said second photo-detecting means detects a part ofthe laser beam emitted from the semiconductor laser and impinging uponthe objective lens.